Circuit breaker



Nov. 24, 1953 w. A. THOMAS ,660,637

CIRCUIT BREAKER Filed Nov. 18, 1949 Figl. Fig.2.

Inventor: William A.Thomas,

fiy fl.

His Attorney.

Patented Nov. 24, 1953 UNITED STATES PATENT OFFICE CIRCUIT BREAKERWilliam A. Thomas, Plainville, Comm, assignor, by mesne assignments, toGeneral Electric Company, a corporation of New York Application-November18, 1949;Serial'No.128,096

(Cl. ZOO-88) fi Claims. 1.

My invention relates to circuit breakers and more particularly to whatare termed air circuit breakers of small size.

A prime object is to provide a circuit breaker of this type that iscompact, simple in construction, flexible in action, highly eflicient inoperation and economical-to manufacture.

Another object is to provide a circuit breaker in which the contacts'areheld closed in'such a manner that they cannot be jarred open.

Another object is toprovide a circuit breaker in which the contactpressure is much greater than the latch pressure.

Many circuit breakers are so constructed that when automatically trippedthe rnanuallyactuated member must begiven two distinct movements inorder to reclose thecircuit. It is one of my objects to provide acircuitbreakermechanism of this type which can be reclosed in the samemanner after automatic tripping as after manual openingthat is, by one:movement of the handle.

It is a more particular object of the invention to provide, in afloating lever type of mam ually operable current responsively trippedelectric circuit breaker, new and improved means for automaticallyresetting the current respon sive latching means after tripping so thatno manual resetting movement is necessary following overcurrent trip,and to do so while providing also trip-free operation.

Another object is .to ensure a lidingengagB- ment of a movable contactagainst a stationary contact in closing a circuit and before breakingthe circuit.

ug the thermostatic latch and 'magneticreIeaSe.

6 is an inside view similar :to Fig. 1 but showing the position of the'parts in the position they occupy when automatically released.

The mechanism is enclosed :between the two parts 1', i of an insulating"housing suitably :secured together for instance by screws or 'rivetsThe angular conductor piece '3 has a circuit moves to the right.

terminal It at one end and a switch contact H at the other end. iheothercircuit terminal l2 is secured in place by the screw It.

The switch member or floating arm it which coacts at one end withcontact H has a pin andslot'connection it, Hi with the walls of thebiinetal strip H5 and has-an armature .221pivoted at 23 between thehousing walls. This armature has a lever arm 2 which extends at an angleto the main armature member and is under pressure of spring 25whichbiases the armature toward the right as viewedin Fig. l. The actionof the biinetal under heat or under the attraction of the magnet is tomove the armature toward the left.

A fioating'ro'cker member 2'! has-a pivot pin 23 which can rotate andslide a slot 28 in the housing. This rocker has a carn-like shoulderwhich coacts with a cam'iic onthe switch arm it.

The actuating lever 35 is pivoted in the housing and has an arm with acam surface 34 which coacts with a cam portion of rocker 2 In the closedcircuit position, tie cam part of the lever 3i tightly holds the rocker2'5 in the position of Fig. l where the tip of the rocker engages ashoulder 515 on thearmature and the cam 29 presses on the cam of thefloating switch member is and holds the spring it under compression andpositively holds the switch memher in the closed circuit position whereit cannot jar loose.

It will be noted that the spring l5 presses the switch 'member !3upwardly so that the cam 33 pressesagainst the cam 25% on the rocker 2'1thus pressing the cam 35 on the rocker 2E the cam 34 on the member 33.

Whenthe lever 31 is manuaily turned toward the left from the position ofFig. 1 the cam 3 3 When earn as passes to the right of cam 35, therockeri'i is free to rise in slot 28'. The rocker thus tiltscountenclockwi so that cam 2S slips overcarn as on switch member l3 andthus permits the spring i5 "to tilt the switch member :13 and open thecircuit with a isnap action.

In case of a heavy surge of current or in case of a gradual load abovethat rated for the air cuit breaker, the armature 22 will be drawn awayfrom rocker member El so that the rocker will tilt counter-clockwisethus disengaging cain 5 from cam 38 and releasing member it so thatspring 15 can suddenly throw the parts to the position of Fig. 6 andbreai; the circuit. In tilting counter-clockwise after latch release theroclrer lever 2i engages a projection 33a on the right end of thecamming arm 33 and rotates the operating lever 3! and the cam 33 in acounterclockwise direction to its circuit opening position.

ith the operating lever 31 and the cam in the circuit opening position,the rocker lever being still pressed upward by the spring tiltsclockwise about the cam surface Gil until the pin 28 comes near the topof the slot '28. This movement resets the rocker lever against apositioning surface of the cam 33 as shown at 20 Fig. 6. From thisposition, the breaker can be reclosed as soon as the latch shoulder 36is reset by simply pressing lever from the 011' position of Fig. to theon position of Fig. 1. It will thus be seen that in this constructionthere is an on position an oil position but no reset position of themanual lever, as is common in many circuit oi-cake In case the rocker His at ically the main spring i5 will me e the itch l3 open the circuiteven if the actua ig lever is manually held in on position. this casethe rocker lever 2i tilts cod, tcr-clcclrwise after latch release underthe action or the spring it, pr ssing against the cam and errgaging thetip 23a of the can: arm the lever is then released, it will fly to theonf po'ition because of the pressure applied to "'lt'i 33a by the rockerlever and the rocker lever 21 will then tilt clockwise as before aboutcam projection until the pin 2:? is near top of the slot it. Themechanism is then ready to reclose the circuit manually, being in theposition of Fig. 6.

This arrangement ensures a trip action in it oh the circuit is broken ata maximum speed v -en the breaker is re eased either manually orautomatically. In either case the cam shoulder is first released formovement upwai to the right. The spring It, pressing the inenicer l3upward a. rai es the pivot pin is o to the top of the slot i l. movementof the pin it causes tl tact tip to slide along the surface of the eta ithus preventing tendency a then slides over .lLLS the the shoulder toraise the rign circuit positon of The has its mash mum power at the verystart of openin movement so as to start the sepaation of t an highspeed. This result in superior interruption in a small ci 'cuit brea erof this type. In fact such a switch has proved to be several tir s asfast as ccinrner :ially comparable break- It possible with this type ofbreaker to obtain contact pressure up 0 seven or the latch pressurewhereas in other small breakers the ratio is as low as one or two toone. The gases resulting from the re formed in the chamber to whenbreaking the circuit are allowed to escape through the tortuous iiformed in the housing '1. Ihis labyrinth is further divided into severalcompartments by the perfo- 4 rated fibre bafiles 42 and 43 which act togradu' ally cool and lower the pressure of the gases resulting from theare. This arrangement ensures a safer breaker free from the usualdangers from fire or flame from the exhaust port.

I claim:

I. In a circuit breaker, a a stationary contact mounted on a rigidnovable switch arm having a pin and connection with said base at one andhaving a movable contact at the other end cooperable with sta tionarycontact, pin and slot connection. providing transverse sliding pivotalinovcment of said arm, a spring said switch intermediate movable contactsaid one end and biasing said switch aria to an open ircuit position,and manually operable carn ming means engaging said swirl, arrnintermediate said oontact and said sprin to for *e to a circuit closingposition locii biasing action of said spring, said release of said manubio mean st sliding said one end of said switc 3. arm tieversely therebyto slide contacts one upon e other and then separating said contacts byrotation of said switch arm about said one end.

2. In a circuit breaker, a stationary contact, a rigid movable switcharm hav ng at one end a movable contact cooperating with said ed contact, means mounting said switch arm at his other end for pivotalsliding movement in a direction transverse of said switch arm, a springone-aging said arm intermediate its ends and biasing said arm to an opencircuit position, switch arin having an inclined camining surface inte.said spring and said one end, and manna y operable actuating meansincluding a pivotally mounting camming projection engaging inclinedsurface and shape-cl to permit abrupt cir-- cuit opening movement ofsaid switch arm, said switch arm when released by cast 1?; projectionfirst sliding transversely on said pivotal mounting to slide saidcontacts one upon other and then turning on said pivotal mounting toseparate said contacts.

3. In a circuit breaker, a base, a switch memoer movably mounted on saidbase, cooperating switch contacts controlled by said switch member,means biasing said switch member to a circuit opening position, a rockerlever mounted on said base intermediate its ends on a sliding pivot formovement into engagement with said switch member, current responsivemeans releasably securing one end of said rocker lever against movement,an actuating cam mounted on said base on a fixed pivot and having anactuating projection engaging said rocker lever to tilt said lever aboutsaid one end thereby to move said switch member between circuit openingand circuit closing positions, said rocker lever when released with saidactuating cam in its circuit closing position tilting about said slidingpivot to release said switch member and engaging said cam to move saidcam to its circuit opening position, and positioning means on said camengaging said og UPOU rocker lever when said can", is in its circuitopenleasably securing one end of said rocker lever against movement, amanually operable actuat ing cam rotatably mounted on said base andhaving a projection engaging said rocker lever inter" mediate said oneend and said slidable pivot to slide said pivot, said rocker arm when somoved engaging said switch arm to close and open said contacts and whenreleased by said current responsive means rotating on said slidablepivot to release said switch member for contact opening movement, meansengaging the other end of said rocker arm when released by said currentresponsive means to rotate said actuating cam to its circuit openingposition, and a positioning surface on said actuating cam engaging saidrocker arm in said circuit opening position of said actuating cam toposition said rocker arm for automatic resetting of said currentresponsive means, whereby normal manual circuit closing movement of saidactuating cam after current responsive opening of said contacts reclosessaid contacts.

5. In a circuit breaker, a base, a rigid movable switch arm mounted onsaid base for pivotal movement about one end, circuit controlling meansactuated by the other end. of said switch arm, a spring fixedly mountedon said base at one end and engaging said switch arm to said arm to acircuit opening position, a rocker lever mounted on said baseintermediate its ends on a sliding pivot for movement transversely ofthe length of said switch arm, said rocker lever having a cammingprojection engaging said switch arm intermediate said spring and saidother end of said switch arm, current responsive means releasablysecuring one end of said rocker lever against movement, and an operatinglever pivotally mounted on said base and including an actuating camengaging said rocker lever intermediate said one end and said slidingpivot, said operating lever including a portion positioned to be engagedby said rocker lever when released to turn said operating lever to itsoff position and said actuating cam having a portion engaging saidrocker lever when said operating lever is in said off position toposition said rocker lever for automatic resetting of said currentresponsive means.

6. In a circuit breaker, a base, a stationary contact mounted on saidbase, a rigid switch arm, means mounting said switch arm on said basefor transverse sliding and pivotal movement at one end, a movablecontact carried by the other end of said switch arm for cooperation withsaid stationary contact, a spring fixedly mounted on said base at oneend and engaging said switch arm at a point intermediate its ends tobias said switch arm to a circuit opening position, a rocker leverdisposed in substantially parallel spaced relation with said switch armand having a camming projection engaging said switch arm intermediatesaid spring and said movable contact, means mounting said rocker leveron said base for transverse sliding and pivotal movement at a pointintermediate its ends, current responsive means releasably securing oneend of said rocker lever against movement, and manually operable meansincluding a rotatable actuating cam pivotally mounted on said base andhaving an actuating projection engaging said rocker lever intermediatesaid one end and its pivotal mounting, said actuating projectionnormally tilting said rocker lever about its said one end thereby topress said camming projection against said switch arm and move saidswitch arm to circuit closing position when said actuating cam is movedto a circuit closing position and said rocker lever when released bysaid current responsive means rotating about its intermediate pivotalmounting to release said switch arm for circuit opening movement, asecond projection on said actuating cam disposed for engagement with theother end of said rocker lever when released by said current responsivemeans to rotate said actuating cam to a circuit opening position, and apositioning surface on said actuating cam to engage said rocker leverand position it for automatic reset of said current responsive meanswhen said actuating cam is in said circuit opening position.

WILLIAM A. THOMAS.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,184,372 Van Hoorn Dec. 26, 1939 2,297,320 Platz Sept. 29,1942 2,300,884 Gano Nov. 3, 1942 2,308,401 Taylor Jan. 12, 19432,328,458 Jackson et a1 Aug. 31, 1943 2,363,606 Maseng Nov. 28, 19442,416,164 Ellis et a1. Feb. 18, 1947 2,424,909 Adam et a1 July 29, 19472,447,652 Jennings Aug. 24, 1948 FOREIGN PATENTS Number Country Date41,861 France Jan. 26, 1933 666,338 Germany Oct. 17, 1938

